DoxyPress is a really nice solution that has received lots of effort from you, and it is quite understandable that not everything can be achieved instantaneously. But if you allow me to suggest, It is my understanding that DoxyPress could bring a feature that is seriously missing on any similar solution on this regards, with respect with the level of details brought by the (already really nice) UML Class Diagrams it can generate.

Making use of the excellent and righteous decision made regarding the usage of cLang for parsing, allowing for "instant" adequacy for new standards and features brought by any language covered by it, perhaps DoxyPress could include data details compatible with UML 2.4/2.5, where visibility, signature, parameter list, return spec, etc is included. (http://www.uml-diagrams.org/class-reference.html)

I know this would demand some (perhaps a lot) of effort, but it would definitely bring a reference to DoxyPress. I've seen lots of people asking around forums "source code reverse engineered UML class diagrams generation", and after all, any solution fall short. Two exceptions could be mentioned, but for solutions that does not have the same scope as DoxyPress to bring also extensive documentation, that I mention here for your reference: